Wearable displays have received broad attention in recent years after smart phones became popular and are well accepted by the market. Wearable displays provide the benefits of hands free operation as well as showing the images to the person who wears the display at a distance same as regular sight. Because of these advantages, there are tremendous needs for wearable displays. However, the conventional near eye displays such as Head Mount Display, Head up Display and Eye Glass Type Display have not provided satisfied wearable display solutions to the viewers, because these conventional devices are often too heavy, too large, and too dark. Furthermore, these conventional wearable displays often have low resolution and many of them do not provide a see-through view and are mostly expensive and can only display small size of images. Therefore, there are urgent needs for providing wearable display devices that are light, small, bright, having high resolution with see-through viewing optical path. It is further desirable that the new wearable devices are inexpensive that can display large image and can be putted on in a stealthy manner without being detected by others that the person is wearing such a wearable device.
As shown in FIG. 1 and FIG. 1A, Kasai et al. disclosed in Patent U.S. Pat. No. 7,460,286 an eye glass as a type of display system that implements optics to provide a see-through capability with a holographic optical element. This display system projects images in the normal direction from a display device along a perpendicular direction for a surface of LCD display, to project the light containing an image that is led into optical wave guide and reflected toward the eye of viewer. However, due to the use of a waveguide, the field of view and resolution are very limited.
As shown in FIG. 2 and FIG. 2A, Mukawa et al. in SID 2008 Digest, ISSN/008-0966X/08/3901-0089, “A Full Color Eyewear Display using Holographic Planar Waveguides”, disclose another eye glass as a type of display system that implements see-through capability with two plates of holographic optical elements. Again, this type of eye glass also uses a waveguide which limits a resolution the images and the field of view.
As shown in FIG. 3, Levola in SID 2006 Digest, ISSN0006-64•SID 06 DIGEST 0966X/06/3701-0064, entitled “Novel Diffractive Optical Components for Near to Eye Displays” discloses another display system implemented by locating LCD device in the middle of two eyes. However, such display system requires large protruded space which enlarges the form factor thus making the device too large and inconvenient as a wearable display system. The above three types of displays are using either holographic optical element (HOE) or diffractive optical element (DOE) and all of these optical displays have fundamental difficulties of large chroma aberration, cross talk of colors, large field curvature aberration and distortion aberration. Mukawa et al. explained how to reduce cross talk of colors using multiple wave guides, which makes the system heavier and thicker and further the efficiency of utilization of light is reduced. Kasai et al. used a single HOE which improves the efficiency of light utilization, however, the other aberrations remains and the FOB (field of view) has to be small so that these aberrations will not be conspicuous. Due to these difficulties, there are urgent needs to provide new and improved wearable display system such that the above discussed problems and limitations can be removed.
As shown in FIG. 4 and FIG. 4A, Li et al. disclosed in Patent U.S. Pat. No. 7,369,317 a compact display and camera module attachable to eye glasses. This eyeglass requires a thick PBS (polarized beam splitter) and the FOB (field of view) is rather small, Additionally, this eyeglass is not stealth since the presence of display is very obvious.
The examples such as that shown in FIG. 1 and FIG. 2 have successfully demonstrated to public that a wearable display with see-through image is possible by using holograms and wave guides. However, due to the size of field of view and resolution these systems have limited usefulness. In order to achieve a very large field of view over 60 degrees and high resolution over 1 million pixels, it is necessary to provide a new innovative system. One perspective of this invention is to disclose a new system and design which enables over 60 degrees viewing angle and high resolution from 1 to 8 million pixels, such as 4K display.